Attachment plug for electric heating devices



I Nov. 2, 1929. I R. H. CUNNINGHAM ATTACHMENT PLUG FOR ELECTRIC HEATING DEVICES Filed July 15, 1927 Patented Nov. 12, 1929 UNITED STATES PATENT, OFFICE.

ROY HERBERT CUNNINGHAM, OF JACKSON, MICHIGAN, ASSIGNOR TO THE REYNOLDS SPRING COMPANY, OF JACKSONQMICHIGAN ATTACHMENT PLUG FOR ELECTRIC HEATING DEVICES Application filed July .15,

This invention relates to an attachment plug for electric heating devices and has for its object to provide a simple, inexpensive, durable and efl'ective device of this nature.

lVith the above and other objects in view, the invention consists in the construction and novel combination and arrangement of parts hereinafter described, illustrated in the accompanying drawings and set forth in the claims hereto appended, it being understood that various changes in the form, size and minor details of construction may be resorted to, within the scope of the claims, without departing from the spirit of the invention ,or sacrificing any of the advantages thereof.

In the drawings:

Fig. 1 is an elevation of one section of the I insulating body, the operative parts being re moved.

Fig. 2 is a longitudinal sectional view ghriough one of the contacts and the insulating Fig. 3 is a a central longitudinal view through the insulating body.

Fig. 4 is an enlarged detail elevation of one of the contacts removed from the insulating body.

Fig. 5 is a' similar view taken from another side of the contact. x

Fig. 6 'isa transverse sectional view of the contact.

Fig. 7 is a end view. Referring now more particularly to the accompanying drawings, the reference character A indicates a body of insulating material comprising two sections 8 and-9 of molded insulating material and each provided with a marginal. rib 10 and having centrally arranged forked ribs B, including the central longitudinal portions 11 and the diverging fork arms 12, these ribs being fitted together to form av brace and division members.

The central longitudinalportions 11 are arranged in spaced relation with the marginal ribs 10 to provide side recesses 13 having smooth walls for the reception of the contacts C. The upper portions of the sections are laterally enlarged to form similar slightly projecting segments 14 serrated exteriorly to of insulating material. tric cord are spread at the top of the forked 1927. Serial No. 205,951.

provide grips for the ready removal of the The insulating body A is provided with a I circular opening 17 through which the electric cord passes, and this cord is passed through a coil spring 18 having an enlarged portion 19 fitting within an annular groove 20 in the wall of the circular opening 17. When the sections of the body A are assembled and clamped together by the fastenings 21, the enlarged portion 19 of the coil spring is securely held in the said annular groove 20 of the plug.

The coiled spring 18 car at its outer end and this bushing is formed The wires of the elecrib A and the ends extended around the outer 'ends of the fork arms 12 and are secured by binding screws 23 of the contacts C of the The contacts C of the heater plug are adapted to fit snugly within the recesses 13 and each is composed of a single strip of copper,

bronze or other suitable conducting material ries a bushing 22' bent at its center to form overlapping p'ortions constituting a shank 24. These portions of the shank are bent outwardly in opposite directions'at the inner end of the shank to provide offset side portions 25 from which are extended the sides 27, which latter at their extremities are flared in rounded formation, as at- 28, away from each other, and thence bent back upon their flaring portions and from the flaring portions directed rea'rwardly in parallelism and overlapping or. in contact contact C has a spring finger 3O struck uptherefrom leaving a longitudinal slot 31 therein. These fingers are yieldable and stand out from the opposite converging sides of the contact and as these fingers press against the walls of the recesses 13 of the plug they give a double spring effect without causing the contact to grip the heater plug wheninserted therein or withdrawn to the extent of causing undue resistance in the passage of the plug into or out of the contact. The sprin fingers 30 render the contacts self-centering, the fingers exerting equal pressure on thewalls of casing sections 8 and 9- and thereby centering the contacts with relation to the openings at the end of the recesses, which insures the reception of the plugs of the iron, toaster, or other device between the tongues 29. This overcomes the possibility of flat or other plugs, especially flat plugs, entering the attachment between one of the sides 27 .of the contact and the wall ofthe plug A, which would be an improper and inefficient or partial contact. Thus the present contact is provided with spring fingers 30 to perform the dual function of overcoming undue wear on the insulating casing and to center the same for the effecting reception of the iron, toaster,

or other plug, irrespective of shape of the latter. This form of contact insures against formation of sharp edges which are liable to cut into the plug body of insulating material when inserting and removing the plug of the i connected device. The present contact is yieldable and cutting of the body of the plug -is overcome and the fingers 30 maintain the present contacts in stated.

The aforesaid longitudinal slots 31 from which said spring fingers 30 are struck are pre:

centered position, as

ferably partially closed, that is, they are closed at their outer ends by the formation of grooves 32 pressed or otherwise formed in and throughout the length of the aforesaid tongues 29. By virtue of the formation of these grooves 32 in the tongues 29 the said slots are intersected by said grooves andpartially closed, as stated, and a full bearing of the metal upon the device inserted in the contact is obtained. As shown, the grooves 32 of the tongues 29 extend through the flarin portions 28 to present a substantially roun or circular mouth at the outer end of the contact, which, together with the flared outer end of the contact, greatly facilitates insert1on of a device into and between the tongues 29 of the contact. I

For the purpose of providing a substantial base of metal to hold the terminal screw 33, a plate 34 is secured to the shank 24 by means of bent fingers 35.- The .plate 34 is provided 'on its outer face with lugs 36 opposite the back rearwardly upon the flared portions and 1 extending between the converging side portions to form tongues lying one upon the other, and yieldable fingers struck up from end extending outwardly from said C0111 verging side portions and resulting in the formation of slots in said converging side portions, said tongues having oppositely disposed longitudinal grooves whereby to substantially embrace an inserted plug, the grooves of said tonguesintersecting the said tongues having oppositely disposed longitudinal grooves extending throughout their.

lengths and leading to the flared ends of the side portions.

3. A contact member comprising asingle piece of metal bent upon itself to form a.

shank and at the free end of the shank ofiset laterally in opposite directions and thence bent to form converging side portions and thence directed rearwardly between said side portions to provide yieldable tongues, the tongues having oppositely disposed longitudinally extending groovesto, receive a plug inserted between the tongues and of-a length to embrace the plug substantially through its'length, and yieldable fingers struck up from the side portions and extending outwardly therefrom. I

4-. A contact member comprising a single piece of metal bent upon itself to form a shank and at'the free end of the shank offset laterally in opposite directions and thence bent to form convergin ing outwardly therefrom and resulting in side portions and thence directedrearwardiy between said side 85 v slots and partlally closing the latter and ex- .my hand.

slots in the side portions, said grooves in said tongues intersecting said slots.

.5. A contact member comprising a single piece of metal bent upon itself to form a shank and at the free end ofthe shank being directed outwardly in opposite directions and thence to provide side portion provided with openings and having their ends flared and thence bent backwardly and extending rear- Wardly between the side portions to form yieldabletongues arranged between said side portions, the said tongues intersecting the openings in the side portions.

- In testimony whereof I have hereunto set RoYHL CUNNINGHAM. v 

